Underfeed stoker



UNDERFEED STOKER Filed Jan. 14, 1956 5 Sheets-Sheet 1 June 27, 19%39. R(ZINKERNAGEI. Err Al. 2,154,100

UNDERFEED sToKER Filed Jan. 14, 1956 5 Sheets-Sheet 2 /.m ATTORNEY June27, 1939.

R. ZINKERNAGEL ET AL UNDERFEED STOKER Filed Jan. 14, 1936 Lf-15.12'. 'tr

5 Sheets-Sheet 3 ATH'ORNEY June 27, 1939 yzlruklzmmslal. ET Al.2,164,100

UNDERFEED STOKER Filed Jan. 14, 1936 5 SheeLS--Shee'll 4 rum- INVENTORSATTORNEY June 27, 1939.- R. ZINKERNAGEL" ET AL. 2,164,100

UNDERFEED sToKER 5 Sheets-Sheet 5 Filed Jan. 14, 1936 INVENTOR ATTORN EYPatented June 27, 19.39

PATENT OFFICE UNDERFEED STOKER Richard Zinkernagel, New York, and GeorgeP.

Jackson, Flushing, N. Y., assignors to Combus- Y tion EngineeringCompany, Inc., New York,

Application January 14, 1936, Serial No. 59,046

7 Claims.

This invention relates to stokers and particularly to the multipleretort underfeed type.

The invention contemplates, in a multiple retort Stoker, a novelassembly of parts so arranged as to cooperate to eifect eicientcombustion of the fuel thereon, which parts do not interfere with eachothers individual functioning.

An object of the invention is to provide a common pusher actuating meansfor each retort cooperating with individual pusher control means, saidcontrol means being independent in control from said actuating means.

A second object of the invention is to provide a novel controlling meansfor the common pusher t actuating means for each retort as well as forthe individual pushers.

`Another object of the invention is to provide a novel pusherconstruction.

Another object is to provide cooling means of the structural supportingmeans of the tuyres and retorts.

A further object of the invention is to provide a novel and simple meansfor the orientation of` the major stoker parts during their assembly,said orienting means serving as major supporting and orientingstructurefor said major stoker parts.

t Still another object of the invention is to provide an overfeedsection construction adapted to minimize clinker formation.

How the foregoing, together with' such other objects and advantages asmay hereinafter appear, or are incident to our invention, are realized,is illustrated in preferred form in the 1 accompanying drawings,Wherein:

Fig. l is a longitudinal sectional view of aV stoker constructed inaccordance with the invention;

Fig. 2 is an enlarged, partly sectional, view of the forward end Yof theStoker showing the arrangement of the orienting beams and also thecommon adjusting control for operating the pushers of a retort; v

Figs. 3 and 4 are sectional views on the lines 3 3 and 4 4 in Fig. 2andillustrate the` construction of the common adjusting control for thepushers of a retort;

Fig. 5 is an elevational view `of the orienting` beams for the retortsas seen from the right 5` hand Sideof Fig. 2, some parts being omittedFig. 7 is a sectional view on the line 1 1 in Fig. 6, partly broken awayshowing the construction of the retorts and tuyres;

Fig. 7A is a sectional view taken on the line 1A TA in Fig. 7;

Fig. 8 is a side elevational View, partly in section, of the overieedsection located beyond the retort illustrated in Fig. 6, and shows thecontrol means for variably regulating the operation of the moving gratebars;

Fig. 9 is an end view, partly sectioned on line 9 9 of Fig. 8, of theoverfeed section;

Fig. l0 is a plan View, partly in section, showing the construction ofthe auxiliary rams or pushers; and

Fig. 11 is a sectional View along line Il ll in Fig. 10 illustrating theindividual controls for regulating the movement of the pushers and alsoshowing the construction of `the latter.

Referring to the drawings, the numeral I designates one of a pluralityof columns spaced at suitable intervals across the width of the Stoker`and-supporting the main beams 2 and 3 which run transversely of theStoker. In the arrangement shown, the beam 2 is a channel beam lying ina vertical position and forming part of the front wall of the Stoker.The beam 3 is an I` beam mounted horizontally near the top of beam 2 sothat the meeting flanges of the beams form right-angle surfaces 2a, 3athat serve as an orientation means for the major parts of the stoker.Fastened on top of beam 2 and also to beam 3 are face plates 4 havingcast integral therewith the main ram cylinders 5, there being one faceplate for each retort of the stoker. Ram box sides 6 are bolted at rightangles to the face plates 4 and have secured thereto the forward ends ofbeams l which at their rear ends rest freely in saddles 8 carried by therear main supporting beam 9, Fig. 8, thereby providing for freedom ofexpansion and contraction. The beams 1 form the main longitudinalsupports for the tuyres and adjoining retorts and also for partsauxiliary thereto, as will be apparent as the description proceeds. Theorientation of the beams 'l by attachment to the ram box sides 6 whichin turn are oriented by being secured to the face plates 4 that arefitted to the rightangled surfaces 2a, 3a formed 'by the beams 2, 3results in the upper end faces of lthe beams 'I being located in thesame plane so that these beams are parallel and thus enables all of the`parts of the alternating retort and tuyre sections of the Stoker to besimply and accurately oriented with relation to each other.

The beams 1 are of box girder construction and constitute air boxes forthe superposed tuyres, the beams being reticulated on their upper andlower faces to provide for the passage of air into the tuyres from theair chamber I beneath the Stoker. Sectional side plates for the retortsand tuyres are secured to the beams 1 as by bolts I2. The plates arespaced from the beams to provide air gaps I3 between the sides of thebeams and the plates. rest upon beams 1 at intervals, as by feet I4,leaving air spaces I between the feet |4. Air may pass from the chamber|0 beneath the stoker around the air boxes |2a below the tuyre blocksthrough the air gaps I3 and spaces I5 and into the tuyres at all times,that is at banking' periods when the air dampers to the tuyres areclosed as Well as during other periods. Thus, the beams 1 are cooled onboth sides by the incoming air for combustion during al1 periods ofoperation and are thereby protected from overheat- The space at thebottom of each retort between its side plates is spanned at intervalslongitudinally thereof by supporting plates 20 on which ridetheauxiliary rams or pushers 2 I, in this Acase four in number. The plates20- are yieldingly fastened to the bottom flanges of the side plates toallow movement for expansion that may occur. The pushers 2| areadjustably connected, for selectively regulating their stroke, as willbe described later, to individual brackets 22 allxed to a rearwardlyinclined reciprocable beam- 40, except the forwardmost pusher 2|, whichas shown in Fig. 2, is carried by rod 14 connected to the forward end ofbeam 40 vfor actuating the latter.- Rod 14 and beam 40 togetherconstitute a pusher bar for reciprocating the-pushers and the slidinggrate bars 5|. Beam 40 is fixed at intervals to plate members 4| formedwith trunnions 4 Ia provided with rollers-42 guided between upper andlower tracks 43, 44 supported by brackets 45- depending from thelongitudinal beams -1.

The-overfeedY section ofthe stoker comprises alternated fixed andmovinggrate bars 50,-5l, respectively, the latter havingslots 52, engaging atransverse rail 53. These bars may befeither solid -or of hollowconstruction.l Similarly to pushers 2|, the` operating stroke of rail 53Vand hence of-bars 5|,-is variable-as will be set forth later. Thereciprocating movement of these bars is effectedin one direction througha member 54 operatively connected to the reciprocable beam 4D 4andin theother direction by means of a rod 55 -xedly connectedaty one end to thebeam.

The main ram' 60, the auxiliary rams or pushers 2| and the grate bars 5|of each retort receive their-motion indirectly from a crank shaft drivenby any suitable means, as a system of selective reduction gears, whichin turn are driven by a motor. The ram 60 is driven by the usual crankand crank pin 6| through a connecting rod 62 carrying a wrist pin 63 foractuating the ram. Crank pin 6| also operates a bell crank 66 through aconnecting rod 61, a pin and slot connection 68, 69 betweenfthese partsproviding lost motion and reducing the amplitude of motion imparted tothe bell crank 66. Y

Bell crank 66 carries a pin 10 extending into,

which togethervwi-th rod 14 constitutes a common` The side plates |IYpusher bar for the four pushers 2| and the alternate, sliding grate bars5| corresponding to the related retort.

The operating stroke of the pushers and grate bars have a commonadjustment comprising a multi-step cam 15, xed to a shaft 13 extendingparallel to the rod 14. Shaft 13 is positioned close to the push rod sothat part of cam 15 is always in the path of movement of pin 10. Onrotation of cam 15 its steps 16 may be selectively interposed betweenthe head of rod 14 and the pin 1D mounted in a link 10a pivotallycarried by bell crank 66 that operates the rod to vary the amount ofmovement imparted to rod 14 from the ram. Cam 15 is adjusted from thefront of the stoker by a hand wheel 11 indexed to correspond with thesteps of the cam. The motion of hand wheel 11 is transmitted to cam 15through shaft 13 which has a telescopic section 13a formed with a slot13b in which a stud 13s is engaged so as to permit reciprocatingmovement of cam 15 with rod 14 while providing for rotative adjustmentof the cam by hand-wheel 11. The reciprocating part of vshaft 13 issupported by bracket 18 as shown in Fig. 3. Thus, by adjusting cam 15 toselectively position the steps thereof to take up more or less of theamount of lost motion permitted by the slots 1| in clevis 12 before pin1U is effective to advance the rod 14, the extent of rearward movementimparted to rod 14v and beam 40 for advancing the pushers 2| and gratebars 5| may be varied.v The pusher bar 14, 4U, and hence the pushers andgrate bars, are returned forwardly to their starting positions by pin onbell crank 66 engaging links 12 at the forward end of the slots 1|.

Each pusher 2| comprises a skeleton cradle 23 which lies below the twoupper plate castings 24, 25 constituting the two steps of the pusherwhich advance the fuel down the stoker. At either side of cradle 23 andbelow plates 24, 25 are pusher side plates 26 which are independentlyfree to move sideways and are held against the retort sides II by meanssuch as springs 21 thereby preventing the-'passage of siftings betweenthe pusher andretort sides. The plates 24, 25 are removable forreplacement and interlock with sideY plates 26 at 28 and with each otherat 29. The sidek plates 26 .iny turn interlock with cradle 23 and aremoved thereby back and forth. A cam 3|] (Figs. 10 and 11) is mounted ona shaft 3| carried by the related bracket22 on the reciprocableactuating beam 40 which constitutes the pusher bar. Cam 30 has steppedsurfaces 32, four steps in this instance, any one of which may .beplaced in position to contact and push cradle 23 forwardly by revolvingthe cam into position manually through the respective indexed hand wheel33 and shaft 3|. The different steps provide a variable lost motionbetween the cam 3|)andV cradle 23 and, consequently, a variable strokeof thepusher. The return stroke is caused by bracket 22 engaging thehook 34 on bolt 35, the bolt in turn drawing the cradle 23 forwardby itscollar 36 engaging a shoulder of the cradle provided therefor. Cradle 23is formed with a vertical slot 31 andwhen bolt 35 Yis revolved throughabout 180 deg., hook 34 will be in a position where .it will passthroughI said slot when .the-bolt is withdrawn. Likewise, hook 34willpass through the slot in bracket 22 so that with the release of thebolt the cradle may be drawn to the right Fig. 1lv and the entire pusher2 IJ with Lit-and free fromy beneath vthe pusher supporting plates20-for the pusher above. 'Ihe step plates 24, 25 of the pusher may thenbe removed by revolving the top plate 24 slightly clockwise around therearward end of bolt 35 and lifting it rearwardly clear, and thenlifting off the plate 25 which forms the lower step. Cradle 23 may thenbe removed if necessary as well as side plates 26. By these novel meansthe pusher parts may be easily renewed from the furnace side, of theStoker, Suitable seals are provided at the front edge of the pusher toreduce the siftings and air leakage which would otherwise pass by.

The different steps of each cam 3l] provide a variable lost motionbetween beam 46, bracket 22 thereon and the related pusher cradle 23 andconsequently enable the stroke of each pusher 2I to be variablyregulated independently of that of the others although all receive theirmotion from the main rod I4 and beam 40 common thereto.

'I'he member 54 for reciprocating the alternate movable grate bars 5I isguided in a bearing 56 and at its forward end is selectively engageableby the steps of a cam 5l similar tothe cams 30 for the pushers 2|. Cam5l is rotatable by a shaft 58 operated from a hand wheel at the front ofthe stoker. Thus, the cam steps which are positioned at differentdistances from the forward en'd of member 54 may be selectively alignedtherewith so that the travel of the movab-le grate bars 5I may be variedas in the case of the pushers 2 I. The rod 55 connected to and movingwith beam 4D is provided with adjustably positionednuts 59 engageablewith the rear end of member 54 for returning rail 53 and hence the gratebars 5I on the forward stroke, the adjustability of nuts 59 permitting alost motion in the stroke. The overfeed section of the present Stokermoves each alternate grate bar- It has been found that greater agitationof fuel results, with resultant avoidance of clinker adhesion and abetter air distribution with better burning. The difficulty of adjacentparallel movements of groups of bars involving a considerable area iscompletely avoided. It has been found that there is a more uniformtransition of fuel flow from the retorts to the overfeed section and amore uniform flow of fuel across the overfeed section. The clinkeradhesion that occurs in the group movement does not occur with this newoverfeed section.

The shafts 3|, 58 for adjusting the stroke regulating cams 36, 5'1 ofthe pushers 2I and reciprocable grate bars 5| all reciprocate as a unitwith the rod 'I4 and beam 46. In order that the hand wheels on theseshafts may be stationary, that is non-reciprocating, telescopic sections3Ia, 58a, similar to those of shaft 13 (Fig. 3) are provided to transmitthe motion of the hand wheels to the shafts through lugs operating inslotted lug ways, lubrication therefor being provided through the hollowportions of the shaft. Universal joints Blu, 58u are provided fortransmitting motion through angularly disposed portions of the shafts.The shafts 3|, 58 are supported beneath the retorts by brackets 46depending from beam 40, as well as by the brackets 22 thereon adjoiningthe pushers. As described above, the beams 40 are reciprocatinglysupported beneath the retort by the trolley members 4I guided on thetracks 43, 44 carried by the main longitudinal box guides l. As shown inFig. 2, the shafts 3l, 58 extend through bearings 4l,

mounted on or adjacent to the main transverse beam 2, that serve as airseals.

Air for combustion enters the chamber I 0 common to all the tuyres whichare disposed transversely of the stoker and extend longitudinallythereof between the retorts. This chamber is limited by the Stoker frontwhich is located in alignment with the main transverse beam 2, andextends rearwardly below the rear supporting beam 9 to beneath theoverfeed section of the stoker. As mentioned above the longitudinallydisposed box girders form air boxes for the tuyres. It may be desirableto have control dampers at the bottom of the supporting beams I4 undereach tuyre whereby the air to each tuyre or portion thereof isindependently controlled.

The arrangement of parts of our improved stoker provides .a common`pusher actuating means for each retort, the stroke of which may bevaried, cooperating with individual and independent pusher control meansfor each pusher and for the overfeed grate bar control means.

What we claim is:

l. In a stoker having a retort, a plurality of pushers therein, areciprocable pusher bar connected to said pushers and a member foroperating said bar; pin and slot means providing a lost motionconnection between said member and said pusher bar; means for variablyregulating the movement imparted to said bar through said connectioncomprising; a shaft extending adjacent said bar and member; a camslidably keyed to said shaft and formed with a plurality of portionsvarying in length in the direction of movement of said bar and adaptedto be individually disposed between the said pin of said connection andsaid pusher bar for regulating the extent of reciprocation of thelatter.

2. In a Stoker having a retort comprising side plates and interveningbottom plates on which pushers are reciprocable to feed fuel along theretort; a pusher in said retort comprising; a frame or cradle; steppedplates mounted on said cradle for supporting and advancing the fuel;side plates freely mounted on said cradle below said stepped plates; andmeans carried by said cradle urging the side plates of said pusheragainst the side plates of said retort.

3. In a stoker having a retort comprising side plates and interveningbottom plates on which pushers are reciprocable to feed fuel along theretort; a pusher in said retort comprising; a frame or cradle; steppedplates mounted on said cradle for supporting and advancing the fuel;side plates freely mounted on said cradle below said stepped plates; andsprings mounted transversely of said cradle and arranged to exertpressure against said pusher side plates for urging them toward the sideplates of said retort.

4. In a stoker; a plurality of spaced retorts comprising side platesextending longitudinally of the Stoker with intervening bottom platesadjacent the lower edges thereof in each retort; tuyre blocks supportedby the adjacent side plates of contiguous retorts; beams extendinglongitudinally of the Stoker below said blocks and disposed adjacent thelower portions of the outer sides of said side plates and spacedtherefrom for providing air passages between said beams and plates; andfeet at intervals on said side plates intermediate the top and bottomedges thereof resting on the tops of said beams to mount said platesthereon and providing openings along the top of said beam between saidfeet communicating with said passages-for admitting air flowing throughsaid passages from below said retorts tothe space above said beams andbelow said tuyre blocks for coolingrthe upper portions of the outersurface of said side plates.

5. In an underfeed stoker having a retort including spaced side platesextending longitudinally of the stoker and bottom plate disposedtherebetween; a pusher for said retort comprising; a frame or cradleadapted to ride on said bottom plates and having a forward portion ofgreater height than its rear portion; a step plate mounted on the lowerrear part of said cradle and having an angular portion extendingdownwardly over the rear side of the lower portion of said cradle; a lugor ange on the forward edge of said plate; a second step plate mountedon the upper forward part of said cradle and having an angular portionextending downwardly in front of said upper part and of the forwardflange on said first plate to lock the latter on the cradle; adownwardly extending lug or flange on the forward edge of said secondplate lockingly engaging the forward face of said cradle; a reciprocablepush bar for actuating said pusher; a bracket on said push bar formed onits upper face with a slot extending longitudinally of the pusher; meanscarried by said bracket and engageable with said cradle for moving it inone direction; and a bolt extending through the angular portion of saidsecond plate and having a lugthereon engageable with said cradle and aportion lying in the slot in said bracket with a second lug at itsforward end engaging said bracket for moving said cradle in the oppositedirection.

6. In an underfeed Stoker having a retort including spaced side platesextending longitudinally of the stoker and bottom plates disposedtherebetween; a pusher for said retort comprising a frame or cradleadapted to ride on said bottom plate and having a forward portion ofgreater height than its rear portion; a step plate mounted on the lowerrear part of said cradle and having an angular portion extendingdownwardly over the rear side of the lower portion of said cradle; a lugor ange on the forward end edge of said plate; a second step platemounted on the upper forward end part of said cradle and having anangular portion extending downwardly in front of said upper part and' ofthe forward end flange on said first plate to lock the latter on thecradle; a downwardly extending lug or flange on the forward end edge ofsaid second plate lockingly engaging the forward end face of saidcradle; a reciprocable push bar for actuating said pusher; a bracket onsaid push bar formed on its upper face with a slot extendinglongitudinally of the pusher; means carried by said bracket andengageable with said cradle for moving it in one direction; and a boltextending through the angular portionof said second plate and having alug thereon engageable with said cradle and a portion lying in the slotin said bracket with a second lug at its forward end engaging saidbracket for moving said cradle in the opposite direction, said boltbeing rotatable in said bracket slot for disengaging said second lugfrom said bracket to permit said pusher being disengaged from and movedaway from said bracket.

7. In a stoker having a retort, a pusher mounted for reciprocationtherein, a reciprocable pusher bar and means for actuating the latter; abracket iixedly carried by said bar for moving said pusher rearwardly insaid retort; a rotatable shaft supported by said bracket for Varying themovement of said pusher; a rotatable member mounted on said shaft andinterposed between said bar-carried bracket and said pusher, said memberbeing formed with a plurality of steps symmetrically disposed about saidshaft and varying in length axially of said shaft for selectivelyengaging said pusher on rotation of said shaft to vary the movement ofsaid pusher by said bar; and means carried by said pusher and engageableby said bar-carried bracket for moving said pusher forwardly.

RICHARD ZINKERNAGEL. GEORGE P. JACKSON.

